Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 24, 2016	Jun. 26, 2015	Jun. 24, 2016	Jun. 26, 2015
Numerator:
Net income (loss)	$ 723	$ 2,207	$ (2,516)	$ 3,380
Shares used in computation — basic:
Weighted average common shares outstanding	32,565	31,615	32,437	31,042
Shares used in computation — diluted:
Shares used in computing basic net income (loss) per share	32,565	31,615	32,437	31,042
Dilutive effect of common shares outstanding subject to repurchase	184	111		232
Dilutive effect of options outstanding	43	51		84
Weighted average shares used in computing diluted net income (loss) per share	32,792	31,777	32,437	31,358
Net income (loss) per share — basic	$ 0.02	$ 0.07	$ (0.08)	$ 0.11
Net income (loss) per share — diluted	$ 0.02	$ 0.07	$ (0.08)	$ 0.11